In general, inkjet printers include at least one printhead that ejects drops of liquid ink onto recording media or an image receiving member. In an indirect or offset printer, the inkjets eject ink onto an image receiving member, such as a rotating metal drum or endless belt, before the image is transferred to print media. In a direct printer, the inkjets eject ink directly onto the media, which may be in sheet or continuous web form. A phase change inkjet printer employs phase change inks that are solid at ambient temperature, but transition to a liquid phase at an elevated temperature. Once the melted ink is ejected onto the media or image receiving member, depending upon the type of printer, the ink droplets quickly solidify to form an ink image.
Printers typically conduct various maintenance operations to ensure proper operation of the inkjets in each printhead. One known maintenance operation removes particles or other contaminants that may interfere with printing operations from each printhead in a printer. During such a cleaning maintenance operation, the printheads purge ink through some or all of the inkjets in the printhead. The purged ink flows from the apertures of the inkjets that are located in a faceplate of each printhead onto the faceplate of each printhead. The ink rolls downwardly under the effect of gravity to an ink drip bib mounted at the lower edge of the faceplate. The bib is configured with one or more multiple drip points where the liquid ink collects and drips into an ink receptacle. In some printers, one or more wipers are manipulated to contact the faceplate of each printhead and wipe the purged ink toward the drip bib to facilitate the collection and removal of the purged ink.
While existing cleaning processes are useful to maintain printheads, removing residual purged ink from the printhead remains a challenge. This challenge is particularly significant in phase change ink printers since the ink in these printers can solidify and adhere to structures in the printer. Specifically, surface tension may cause a small portion of the purged ink to remain in contact with the printhead or the drip bib after the cleaning process. The solidified ink may interfere with imaging operations if the solidified ink breaks free from the printhead faceplate or drip bib. The released solid ink may contact a web or other image receiving member as the image receiving member moves past printheads in the print zone. The solidified ink may negatively affect image quality on the image receiving member, and the image receiving member may carry the solidified ink past one or more printheads in the print zone. Since printheads are often positioned a short distance from the image receiving member, the solid ink may contact the faceplate of one or more printheads with possibly adverse consequences. Thus, improved printhead cleaning is desirable.